FRINGE SCIENCE

Glaciers: The Newest (Fictional) Threat to Mankind

In the Arctic Circle, volcano eruption unleashes a glacier that will destroy mankind … at least, according to the trailer for 2012: Ice Age, a fun (and funny) B-movie featuring the destruction of New York City by a glacier – a really, really fast 1,000 miles long glacier set off by a volcano in the Arctic Circle.

It's one of those disaster movie plots too silly to ring true, but over here at The Exchange, we couldn't help but wonder, “What if?” Could a glacier ever move that fast or be that big? Is there a known glacier threat to New York City?

Well, says Thomas Wagner, NASA’s program scientist for the cryosphere, the short answer is no. “Glaciers don’t move like that, there are no candidate glaciers anywhere near a major city, and a volcanic eruption beneath one wouldn’t have that affect.” Bummer. “It could speed it up a bit by melting it and lubricating the bed, and perhaps even cause some flooding downstream, but this implies that some major glacier is hanging there in the balance. They don’t really work like that,” explained Wagner. “Snow builds up, they thicken and flow much like pouring thick syrup on a plate.”

But What Could Happen…

Okay, so no “volcano causing a giant, fast glacier headed for a major city” in real life. But in talking to Wagner, something much more fascinating (and scientifically plausible) came to light. Volcanic-ice interactions, he told us, could – and have – caused some major disasters. “What’s intriguing about the film trailer is they took it to the extreme by saying ‘Hey, let’s have a bulldozer of ice barrel down on New York,’” said Wagner. “Well, maybe that’s not the real threat but there are a lot of volcano-ice threats.”

The most recent volcanic-ice interaction is the volcanic eruption at Eyjafjalla Glacier in Iceland in April 2010, during which magma interacted with the ice covering the volcano, causing an explosion of magma and throwing particles of frozen silicate magma tens of miles into the air. The resulting volcanic ash plume disrupted air travel for weeks.

That is the tip of the iceberg though. The real danger, Wagner explained, are lahars, mudflows caused by volcanic eruptions melting glaciers and snow fields. In 1985, lahars (which look and behave like flowing concrete) killed more than 20,000 people in Columbia when the Nevado del Ruiz volcano erupted, melting the surrounding glaciers and sending four lahars down the mountain at 40 miles per hour.

The same threat looms over Seattle, Washington, with the nearby active volcano, Mount Rainier. According to the U.S. Geological Survey (USGS), past lahars from Mount Rainier traveled at speeds of 45 to 50 miles per hour and were as much as 100-feet thick or more. The USGS also reports that nearly 80,000 people live in Mount Rainier’s lahar-hazard zone, so while a glacier destroying New York City is far-fetched, a lahar devastating Seattle is a real concern.

Volcanoes Under Antarctica?

While a fast-traveling glacier hitting New York City is implausible, Wagner was quick to point out the basic premise of 2012: Ice Age comes from a place of real science. “The fascinating thing is there are a bunch of volcanoes under ice in various places around the world,” he said. “It ranges from the volcano in Columbia, where there were snow fields and small glaciers on top of a volcano – which turned out to be tremendously dangerous – all the way to Iceland where you have moderate-size glaciers with volcanoes under them. When those erupt, the magma hits the ice, literally exploding and throwing out these clouds of ash. Then on top of that you have what we think are active volcanoes completely covered by ice in Antarctica.”

Hold up. Wait a minute. Did he say there were volcanoes under Antarctica? “The West Antarctic Ice Sheet has some active volcanoes under it,” Wagner explained. “When we go drill ice cores, we can see layers of volcanic ash in those cores from volcanic eruptions.” It does not appear that any of the previous eruptions had a major effect but for creative purposes like a disaster flick, the possibility is there.

But even if an eruption occurred in Antarctica, it would not create a glacier. (Even if it did, the glacier would not be near a major city.) So where’s the disaster? “It’s thought that if West Antarctica melted, it might raise global sea levels by 10 feet or more,” said Wagner. “No one thinks it’s going to melt all at once but there are some ideas that it could cause sea levels to rise rapidly because it looks like it’s very unstable in places.”

So unstable, in fact, that a volcanic eruption could potentially dislodge the ice. West Antarctica is a “marine-based” ice sheet, meaning it rests on a bed below sea level (in this case, close to a half a milebelow sea level). If the rate at which the ice flows into the ocean is sped up by a volcanic eruption, it could thin to the point that it lifts off the bed and floats into the ocean, where it would melt and raise sea levels. “Suppose you had a glass filled up with ice and you poured Coca-Cola into it,” Wagner explained. “You’ve got ice all the way to the bottom of the glass. Well, as that ice begins to melts, it reaches a point where it sort of pops off the bottom and begins to float. That’s what we’re talking about.”

Armadas of Icebergs

Let’s put aside volcanoes for now and look at some dramatic, historical glacier events. The first is Lake Agassiz, a massive glacial lake located in North America during the last glacial period (“the last Ice Age”). “There’s a theory that when that lake drained out, it actually caused the Arctic Ocean to freeze over and it delayed the end of the Ice Age,” Wagner explained. Then there are Heinrich events, when continent glaciers disintegrate quickly, flooding the Atlantic Ocean with an armada of icebergs. “So many icebergs,” said Wagner, “that as these icebergs get out into the ocean and melt, they drop the sediment that’s frozen into their base and you can see it in ocean drilling cores.”

These are events that likely will not happen again. “We don’t have anything today that could produce a Heinrich event,” said Wagner, but the storytelling potential is there with real science to back it up. “Picture this vast armada of ice released into the Atlantic Ocean – what it would wreak havoc on,” Wagner described. “Think of this massive lake drained into the Arctic Ocean – it would freeze over the Arctic Ocean and throw the planet into an Ice Age for another 5,000 years. This is the kind of stuff we’re talking about that looked like it might have really happened.”

You have to admit, it sounds more like fiction than science. But it is all real science – which is crazy to think about. Armadas of icebergs, mudflows threatening Seattle, volcanoes under Antarctica – all true. And as Wagner reminded us, there is more to come. “The planet has a lot in store for us."

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“What’s intriguing about the film trailer is they took it to the extreme by saying ‘Hey, let’s have a bulldozer of ice barrel down on New York. Well, maybe that’s not the real threat but there are a lot of volcano-ice threats.”

According to the U.S. Geological Survey (USGS), past lahars from Mount Rainier traveled at speeds of 45 to 50 miles per hour and were as much as 100-feet thick or more.

"The West Antarctic Ice Sheet has some active volcanoes under it. When we go drill ice cores, we can see layers of volcanic ash in those cores from volcanic eruptions.”

You have to admit, it sounds more like fiction than science. Armadas of icebergs, mudflows threatening Seattle, volcanoes under Antarctica – all true.